Stable dishwashing compositions containing sodium dichloroisocyanurate



United States Patent STABLE DHSHWASHING COMPOSITIONS CON- TAINING SODIUM DICHLOROKS'OCYANU- RATE Duncan S. Corliss, Roselle, N.J., Russell R. Keast, Yardley, Pa., and John S. Thompson, Princeton Junction, N.J., assignors to FMC Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed June 18, 1965, Ser. No. 465,182

8 Claims. (Cl. 252-99) ABSTRACT OF THE DISCLOSURE A stable, dishwashing composition having high stability against loss of available chlorine containing 10 to 50% of an alkali metal silicate, 10 to 30% of either sodium hydroxide or potassium hydroxide, 2 to 6% by weight of sodium dichloroisocyanurate, 20 to 60% of a sodium or potassium polyphosphate and 0.5 to of a lowfoaming nonionic surface active agent compatible with said sodium dichloroisocyanurate.

This invention relates to detergent compositions useful as cleaners and, more specifically, to those compositions containing sodium dichloroisocyanurate which are useful in dishwashing machines.

In the formulation of dishwashing compositions it is common to incorporate known detergent builders such as sodium tripolyphosphate with inorganic salts such as sodium metasilicate, sodium carbonate and others. In addition the more effective detergent compositions also include highly alkaline materials such as sodium hydroxide for improved cleaning and chlorinating agents such as chlorinated cyanuric acids and their salts as destainers and germicidal agents.

One serious problem that has arisen with these compositions is the undue loss of available chlorine which results when highly alkaline compounds such as caustic soda and an active chlorine containing compound are blended together in a powdered composition. One attempt to overcome this problem is set forth in U.S. Patent 3,166,513 issued to William G. Mizuno et al. wherein the active chlorine containing material is potassium dichlorocyanurate and its rate of chlorine loss is substantially reduced in the presence of sodium hydroxide by using a granulated form of potassium dichlorocyanurate having a critical particle size. The potassium salt of dichlorocyanuric acid is utilized in this patent because this salt has been considered to be more stable than others. While this patent offers an improvement in producing a more stable formulation, unacceptable loss of available chlorine still results on storage.

As a result there is a need and a demand for a dishwashing composition having good storage stability against loss of available chlorine and good cleaning power which incorporate high alkaline compounds and salts of chlorinated isocyanuric acid.

It is a principal object of the present invention to provide a dishwashing preparation which fulfills these needs.

It is a further object of the present invention to provide a dishwashing preparation containing sodium dichloroisocyanurate and highly alkaline compounds which has a greater resistance to loss of available chlorine on storage than has been obtainable.

These and other objects of the present invention will be apparent from the following description.

We have found that the dishwashing composition set forth below has improved stability against loss of available chlorine normally resulting from the blending of caustic and a salt of dichloroisocyanuric acid in a powdered composition; the dishwashing composition contains as essential ingredients:

(1) An alkali metal silicate having a M 0 to SiO mol ratio of 0.521 to 1.5:], M being either sodium or potassium.Fr0m about 10 to about 50% preferably about 20 to about 40%.

(2) Sodium hydroxide or potassium hydroxide.From about 10 to about 30% preferably about 15 to about 25%.

(3) Sodium dichloroisocyanurate.-From about 2 to about 6%, preferably about 3 to about 5%.

(4) A polyphosphate having an R 0 to P 0 mol ratio of 1:1 to 2:1, R being either sodium or potassium. From about 20 to about preferably about 40 to about 50%.

(5) A low-foaming nonionic surface active agent compatible with chlorinated isocyanurates.From about 0.5 to about 5%, preferably about 1 to about 3%.

We have further found that sodium or potassium hydroxide and alkali metal silicate in the above formulation can be replaced by an equivalent amount of a more alkaline silicate yielding a dishwashing composition having even more improved stability of its available chlorine content; the preferred composition contains as essential ingredients:

(1) An alkali metal silicate having a M 0 to SiO mol ratio of at least 2:1, M being either sodium or potassium.From about 10 to about 50%, preferably about 30 to about 50%.

(2) Sodium dichloroisocyanurate.From about 2 to about 6%, preferably about 3 to about 5 (3) A polyphosphate having an R 0 to P 0 mol ratio of 1:1 to 2: 1, R being either sodium or potassium-From about 20 to about 60%, preferably about 40 to about 50%.

(4) A low-foaming nonionic surface active agent compatible with chlorinated isocyanurates.--From about 0.5 to about 5%, preferably about 1 to about 3%.

It is most unexpected to find that sodium dichloroisocyanurate, in the presence of the above nonionic surface active agent, is more stable in caustic containing formulations than potassium dichloroisocyanurate. The potassium salt has been considered to be more stable than sodium dichloroisocyanurate by those skilled in the detergent art and has been employed in formulations whenever free caustic is present therein. Moreover, the addition of a nonionic surface active agent to formulations containing free caustic and potassium dichloroisocyanurate does not yield the increased stability which is obtained with formulations foam in the dishwasher and prevent the physical cleansing action of the dishwashing composition. Secondly, the non ionic surfactant functions in some unknown manner to prevent loss of active chlorine supplied by the sodium dichloroisocyanurate component when this composition remains in storage prior to use. The nonionic surfactant composition is a low foaming material per se and must be compatible with the chlorinated isocyanurates in that it must not decompose these chlorinated compounds on storage.

Nonionic surfactants which meet these requirements include the lower alkyl ethers of polyoxyethylated octylphenols such as those sold under the Triton CF trade name, for example Triton CF-54" which is the butyl ether of polyoxyethylated octylphenol; an alkylether of polyoxyethylated alkanol such as Surfactant DF-12 polyoxyalkylene glycols having a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains, the hydrophilic chains consisting of linked oxyethylene radicals and the hydrophobic chains consisting of linked oxypropylene radicals, said product having three hydrophobic chains linked by two hydrophilic chains, the central hydrophobic chain constituting 30% to 34% by weight of the product, the terminal hydrophobic chains together constituting 31% to 39% by weight of the product, the linking hydrophilic chains together constituting 31% to 35% by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3000 to 5000, all as described in US. Patent 3,048,548; the alkyl polyoxyalkylene ether alcohols based on straight chain biodegradable hydrophobic segments, for example Tretolite H-03 07S and, the water soluble benzyl ether of octylphenol condensed with ethylene oxide. Other nonionic surfactants are suitable for use in the herein dishwashing preparations and it is not intended to exclude any surfactant possessing the above properties.

The polyphosphate component functions as a water softener and a detergent builder. Polyphosphates of commerce, having an Na O or K to P 0 mol ratio of about 1:1 to 2:1 can be used. Typical polyphosphates of this kind are the preferred sodium tripolyphosphate, sodium hexamethaphosphate and sodium pyrophosphate as well as the corresponding potassium phosphates. The particle size of the polyphosphate is not considered critical and any finely divided commercially available product can be employed.

The formulation may also include either sodium hydroxide or potassium hydroxide as alkaline agents to increase the alkalinity of the overall formulation. It is well known that as a rule the more alkaline the solution the better the cleansing action. The use of either sodium hydoxide or potassium hydroxide increases the alkalinity of the overall compound to the value needed in the cleaning agent. In general, when sodium hydroxide or potassium hydroxide is used in the formulation it is employed with an alkali metal silicate having an M 0 to SiO mol ratio of about 0.5:1 to 15:1, M being either sodium or potassium. However, the sodium hydroxide or potassium hydroxide can be omitted from the present formulation and replaced with a more alkaline alkali metal silicate having an M 0 to SiO mol ratio of at least 2:1, e.g., sodium orthosilicate.

In the present formulation the alkali metal silicate acts as a detergent builder and enhances the cleaning action. The silicate also acts as a corrosion inhibitor for metal parts of the dishwashing machine. More unexpectedly, however, when a more alkaline alkali metal silicate is used such as one having an M 0 to SiO mol ratio of at least 2:1, M being sodium or potassium, in the absence of NaOH, the formulation becomes markedly resistant to loss of available chlorine on storage. These more alkaline silicates obviate the need for adding NaOH or KOH to the formulation to maintain the alkalinity of the formulation at a desired level. Our preferred formulations 4 are those containing no raw caustic compounds such as NaOH and KOH and which are made up with alkali metal silicates having M 0 to SiO mol ratios of at least 2: 1.

Typical alkali metal silicates which can be used in the formulation are those particulate silicates which are anhydrous or which contain waters of hydration. These include anhydrous sodium metasilicate (which is preferred for use with NaOH or KOH); GD Silicate which is a product having an Na O to SiO ratio of 0.521 and typically available in the form containing bound water in the amount of 18.5%.

In addition to the above ingredients the present formulation may employ soda ash (sodium carbonate) in amounts preferably up to about Larger amounts can be used to make up the balance of the formulation. This acts as a filler to give bulk to the formulation and as an anti-caking agent to assure free flow of the formulation. The soda ash also can be used as a source of alkalinity to reduce the amount of either the hydroxide or silicate component needed to achieve the desired alkalinity level.

While the above constitutes the essential ingredients of the composition it is to be understood that additional ingredients such as fillers, e.g., sodium chloride, sodium sulfate, etc., coloring agents and perfumes may also be added without departing from the basic formulation.

While the above ingredients may be mixed in any desired order. best results are obtained when the nonionic surfactant is added to the alkali metal hydroxide and/or the alkali metal silicate with good mixing. This is also desirable because the nonionic surfactant is a liquid and is readily absorbed by the particulate alkali metal hydroxide and/or alkali metal silicate. In preparing the formulation, the alkali metal hydroxide and/or alkali metal silicate are mixed with the nonionic surfactant followed by the addition of sodium carbonate (when employed), sodium tripolyphosphate and sodium dichloroisocyanurate. Each of these ingredients is added with vigorous mixing so that the particulate formulation is substantially homogeneous with a minimum of segregation of any given ingredients. Normally it is advisable to use ingredients having approximately the same particle size in order to prevent segregation on storage.

The following examples are given to illustrate the present invention and are not deemed to be limiting thereof.

EXAMPLE 1 Runs A to FPr0cess of the invention-The followformulations were made up by blending them in the order listed. The only liquid component, the nonionic surfactant, was added to the sodium hydroxide and/0r sodium silicate with careful mixing so that all of the liquid component was distributed and absorbed uniformly.

Formulation (Percent by wt.)

i i D E I l l Sodium orthosilii-ate 48 l 48 48 l 0 0 0 Sodium hydroxide... 0 t) 0 .20 20 Sodium inotnsilicdto 0 0 l 0 23 23 23 Triton (F-54" 1 0 O l 0 [l Surfactant l)F l2 0 l l 0 0 t] 'Tretolite ll()307 S". l 0 0 l 0 0 l Sodium carbonate... 0 l 0 0 l 3 3 3 Sodium tripolyphosphate... l 47 47 47 411 49 Sodium dlL'lllOI'OlSQUYiJ/HUIatG. 4 l 4 4 4 4 The formulations were tested to determine the percent loss during storage for one week under accelerated storage conditions. This was accomplished by placing the granular formulations in a 250 ml. wide-mouth Erlenmeyer flask which was covered with a taped-on piece of paper-polyethylene laminate and placing these permeable flasks in an oven maintained at a temperature of :2"

F. and 80 relative humidity for one week. Thereafter, they were removed and tested for loss of available chlorine and their defoaming properties. The loss of available chlorine was determined by performing a standard iodometric analysis of the formulations before and after storage and determining the loss of available chlorine.

The defoaming properties of certain of the formulations were determined as follows. Each sample that was tested was dissolved in sufiicient water to give a concentration of 0.35% and 250 ml. of this solution was warmed to 140 F. and placed in a one-quart Waring blender. To this mixture was added 0.35 g. of a commercial dried milk product (Starlac was used in this test). The blender was then run at high speed for two minutes. Thereafter the blender was stopped and the average foam height from liquid to the top of the foam was measured in centimeters one minute after the blender was stopped. The loss of available chlorine is reported in Table I, while the foam height of the selected samples is reported in Table II.

Runs G to I-Formulati0ns made up using potassium dichloroisocyanurate in place of sodium dichloroisocyanurate.The following formulations were made up by mixing the ingredients in the order listed below.

Formulations (Percent by wt.) Component G H I Sodium hydroxide Sodium metasilicate Triton CF-54" Surfactant DF-12 Tretolite H-0307-S Sodium carbonate.

Sodium tripolyphosphate 4 Potassium dichloroisocyanurate.

TABLE I Alkali metal Dichloroisocyanurate Loss of Available Chlorine Free Caustic Present Surfactant Triton (IF-54 Tretolite H-0307-S None TABLE II Run Surfactant Foam Height (0111.)

I None A- riton CF54 Tretolite H-0307 Triton Gif -54"-- pe r-s- Formulations A through F were tested in an automatic dishwasher and were found to give excellent cleaning power both before storage and after storage for one week under accelerated storage conditions as reported above.

The percent loss of available chlorine in Runs G, H and I in which the alkali metal dichloroisocyanurate used was the potassium salt is markedly higher compared with those formulations containing sodium dichloroisocyanurate. It should be noted that the degree of stabilization of available chlorine is dependent upon the particular surface active agent used. Moreover, note that when the free caustic is obviated by the use of a more alkaline silicate as in Runs A, B and C that the loss of available chlorine drops markedly over compositions containing caustic, namely, Runs D, E, and F. Further, Table II indicates that the foam heights of the dishwashing compositions A, C and D which contain various surfactants is markedly improved over a similar composition, Run I, in which no surfactant is present.

Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art, such exemplification including what is considered to represent the best embodiment of the invention. However, it should be clearly understood that, within the scope of the appended claims, the invention may be practiced by those skilled in the art, and having the benefit of this disclosure otherwise than as specifically described and exemplified herein.

What is claimed is:

1. A dishwashing detergent composition having good stability against loss of available chlorine which contains as essential ingredients:

(a) from 10 to 50% by weight of an alkali metal silicate having an M 0 to SiO mol ratio of 0.521 to 1.5 :1, wherein M is sodium or potassium,

(b) from 10 to 30% by Weight of a member selected from the group consisting of sodium hydroxide or potassium hydroxide,

(c) from 2 to 6% by Weight of sodium dichloroisocyanurate,

(d) from 20 to 60% of a polyphosphate selected from the group consisting of sodium polyphosphates and potassium polyphosphates having an R 0 to P 0 mol ratio of 1:1 to 2:1, wherein R is sodium or potassium, and

(e) from 0.5 to 5% by weight of a low-foaming nonionic surface active agent compatible with said sodium dichloroisocyanurate.

2. Composition of claim 1 in which the alkali metal silicate is sodium metasilicate.

3. Composition of claim 1 in which the member in part (b) is sodium hydroxide.

4. Composition of claim 1 in which the polyphosphate is sodium tripolyphosphate.

5. A dishwashing detergent composition having good stability against loss of available chlorine which contains as essential ingredients:

(a) from 10 to 50% by weight of an alkali metal silicate having an M 0 to SiO mol ratio of at least 2:1, wherein M is sodium or potassium,

(b) from 2 to 6% by weight of sodium dichloroisocyanurate,

(c) from 20 to 60% by weight of a polyphosphate selected from the group consisting of sodium polyphosphates and potassium polyphosphates having an R 0 to P 0 mol ratio of 1:1 to 2:1, wherein R is sodium or potassium, and

(d) from 0.5 to 5% by weight of a low-foaming nonionic surface active agent compatible with said sodium dichloroisocyanurate.

6. Composition of claim 5 in which the alkali metal silicate is sodium orthosilicate and is present in amounts of from 30 to 50% by weight of the composition.

7. Composition of claim 5 in which the polyphosphate is sodium tripolyphosphate.

8. A dishwashing detergent composition having good stability against loss of available chlorine which contains as essential ingredients:

(a) from 10 to 50% by weight of sodium. orthosilicate,

(b) from 2 to 6% by weight of sodium dichloroisocyanurate, (c) from 20 to 60% by weight of sodium tripolyphos- 8 References (Iited UNITED STATES PATENTS 3.166513 1/1965 Mizuno et a]. 252-99 3,248,330 4/1966 Feierstein et a1. 252-99 3,255,117 6/1966 Knapp et a1 252-99 LEON D. ROSDOL, Primary Examiner.

M. WEINBLATT, Assistant Examiner. 

1. A DISHWASHING DETERGENT COMPOSITION HAVING GOOD STABILITY AGAINST LOSS OF AVAILABLE CHLORINE WHICH CONTAINS AS ESSENTIAL INGREDIENTS: (A) FROM 10 TO 50% BY WEIGHT OF AN ALKALI METAL SILICATE HAVING AN M2O TO SIO2 MOL RATIO OF 0.5:1 TO 1.5:1 WHEREIN M IS SODIUM OR POTASSIUM, (B) FROM 10 TO 30% BY WEIGHT OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE OR POTASSIUM HYDROXIDE. (C) FROM 2 TO 6% BY WEIGHT OF SODIUM DICHLOROISOCYANURATE, (D) FROM 20 TO 60% OF A POLYPHOSPHATE SELECTED FROM THE GROUP CONSISTING OF SODIUM POLPHOSPHATES AND POTASSIUM POLYPHOSPHATES HAVING AN R2O TO P2O5 MOL RATION OF 1:1 TO 2:1, WHEREIN R IS SODIUM OR POTASSIUM, AND (E) FROM 0.5 TO 5% BY WEIGHT OF A LOW-FOAMING NONIONIC SURFACE ACTIVE AGENT COMPATIBLE EITH SAID SODIUM DICHLOROISOCYANURATE. 